Dec. 12 (Bloomberg) -- Paris was put on an air-pollution
alert today as cold weather entrapped diesel fumes, leading to
the most severe smog in the French capital since 2007.

The pollution index for the French capital reached the
highest of five levels for fine particulates, according to
Airparif, which monitors air quality. The government urged
reduced auto speeds on main roads and asked people to refrain
from driving diesel vehicles lacking proper filters and from
lighting up wood fireplaces.

“Irresponsible policies” that encourage the use of diesel
are causing the pollution, Deputy Paris Mayor Anne Hidalgo said
today on France Info.

The pollution alert may reignite debate over taxes on
diesel fuel, which in France are lower than for gasoline.
Environmental groups have urged the government to align the
levies while carmakers such as PSA Peugeot Citroen have resisted
the move.

The pollution alert today was extended to a dozen French
regions hit by a cold snap that has pushed temperatures below
freezing in the past few days and is expected to last through
tomorrow. The warnings included Alsace and Normandy as well as
the southern Mediterranean area around Nice.

“Bad air quality from particulates” can provoke allergic
and asthmatic symptoms, Environment Minister Philippe Martin
said in a statement.

Airparif put its air-pollution index at the highest level
because the concentration of so-called PM10s is poised to be
greater than 100 micrograms per cubic meter.

“The current period of pollution is equivalent to one last
experienced in 2007,” Arthur de Pas, a spokesman for Paris-based Airparif, said by telephone.

Paris Air

France has been put on notice by the European Commission
for not respecting rules on emissions of PM10, which refers to
particulates less than 10 micrometers in diameter.

Airparif has warned in the past that residents of the
French capital suffer from “chronically high levels” of
pollutants such as nitrogen dioxide and particulates.

For today, the Paris mayor made residential parking free in
a bid to get people to leave their cars at home and use mass
transit. Speed limits were lowered along the Parisian ringroad
and major arteries leading to the French capital that are
typically clogged with commuters during weekdays, the Paris
mayor’s office said on its website.

Earlier this month, Shanghai warned children and the
elderly to stay indoors as the level of the most harmful
pollutants exceeded more than 10 times the level deemed safe by
the World Health Organization.